Question

1) You've measured the parallax angles for two stars. The parallax of star A is 0.5 arcsecond, while that of star B is 0.1 arcsecond. Which of these correctly compares their relative distances? (Star A is 5× further away, Star A is 5× closer, Star A is 25× further away, Star A is 25× closer) 2) The difference in energy between the 2nd and 3rd energy states in hydrogen is 1.89 eV (eV = a unit of energy). If a hydrogen atom's electron lies in the 2nd energy state, then what kind of photons can excite this atom's electron to the 3rd energy state? (a) Nature does not allow electron excitations by photons; (b) those with energies greater than 1.89 eV; (c) those with energies less than 1.89 eV; (d) those with energies equal to 1.89 eV.) 3) If you measure a star's parallax angle and apparent brightness, what further information about the star can you derive? (No choices provided here; be specific....) 4) Two stars have the same surface temperature, and the radius (or size) of one star is 1/3 (one-third) that of the other. How do the stars' luminosities compare? (The smaller star is: 3 times as luminous, 9 times as luminous, 1/3 as luminous, 1/9 as luminous - as compared to the larger star.) 5) Stars A and B have equal apparent brightnesses. However, star A's measured parallax is 1/3 that of star B's parallax. How do their luminosities compare? (Star A is: 9 times more luminous, 3 times more luminous, 1/3 as luminous, 1/9 as luminous)

          1) You've measured the parallax angles for two stars. The parallax of star A is 0.5 arcsecond, while that of star B is 0.1 arcsecond. Which of these correctly compares their relative distances? (Star A is 5× further away, Star A is 5× closer, Star A is 25× further away, Star A is 25× closer)

2) The difference in energy between the 2nd and 3rd energy states in hydrogen is 1.89 eV (eV = a unit of energy). If a hydrogen atom's electron lies in the 2nd energy state, then what kind of photons can excite this atom's electron to the 3rd energy state?
(a) Nature does not allow electron excitations by photons; (b) those with energies greater than 1.89 eV; (c) those with energies less than 1.89 eV; (d) those with energies equal to 1.89 eV.)

3) If you measure a star's parallax angle and apparent brightness, what further information about the star can you derive? (No choices provided here; be specific....)

4) Two stars have the same surface temperature, and the radius (or size) of one star is 1/3 (one-third) that of the other. How do the stars' luminosities compare?
(The smaller star is: 3 times as luminous, 9 times as luminous, 1/3 as luminous, 1/9 as luminous - as compared to the larger star.)

5) Stars A and B have equal apparent brightnesses. However, star A's measured parallax is 1/3 that of star B's parallax. How do their luminosities compare? (Star A is: 9 times more luminous, 3 times more luminous, 1/3 as luminous, 1/9 as luminous)

1) You've measured the parallax angles for two stars. The parallax of star A is 0.5 arcsecond, while that of star B is 0.1 arcsecond. Which of these correctly compares their relative distances? (Star A is 5× further away, Star A is 5× closer, Star A is 25× further away, Star A is 25× closer)

2) The difference in energy between the 2nd and 3rd energy states in hydrogen is 1.89 eV (eV = a unit of energy). If a hydrogen atom's electron lies in the 2nd energy state, then what kind of photons can excite this atom's electron to the 3rd energy state?
(a) Nature does not allow electron excitations by photons; (b) those with energies greater than 1.89 eV; (c) those with energies less than 1.89 eV; (d) those with energies equal to 1.89 eV.)

3) If you measure a star's parallax angle and apparent brightness, what further information about the star can you derive? (No choices provided here; be specific....)

4) Two stars have the same surface temperature, and the radius (or size) of one star is 1/3 (one-third) that of the other. How do the stars' luminosities compare?
(The smaller star is: 3 times as luminous, 9 times as luminous, 1/3 as luminous, 1/9 as luminous - as compared to the larger star.)

5) Stars A and B have equal apparent brightnesses. However, star A's measured parallax is 1/3 that of star B's parallax. How do their luminosities compare? (Star A is: 9 times more luminous, 3 times more luminous, 1/3 as luminous, 1/9 as luminous)

Added by Todd T.

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